Fluid pump



Aug. 21, 1945.

' J. F. HOFFER mum Ppur Filed Aug. 26, 1942 2 Sheets-Sheet 1 dzmes F/affer ///0rney INVENTOR.

Patented Aug. 21, 1945 opposite the endwise components 7 within the rotor. but nevertheless end to produce wear by pressing the tapp'ets toward, one side of the tappet-guide bores. Ihe;wea conditions obviously become more pron unced as; hespeed and the pressure increases. cco mpljshing the object first stated the inrovides comparatively small diameter relatively large diameter tap-pets. of the diameter of the pistons pertavorable length to diameter ratio largeness of the diameter of the tappets p large bearing surface and therefore tends to lessen'wear in the presence of the above mention engthwise pressure component.

civantage of the particular piston and rr ngement is that the cylinder bores gthQPiStOIlS need not be accurately he tappet-guide bores which receive Furthermore, as compared with a where the piston and tappet might ed in one piece and therefore connected ar n.

or where the piston itself acts as the taupe a I my co-pending application above rem1: ferr t a distinct advantage exists in the respect at each piston may be formed with a good h drau ic tfit in the cylinder bore while each tappet hasa good free-running mechanical fit in its tappet-guide bore. A piston, inorder to proc 0fv;i c1 e a; good hydraulic seal for extremely high pressures must fit the cylinder bore within a few ten;thousandths of an inch. Under such conditignsthe-hydr'aulic drag becomes extremely high so;th a,t if the piston and tappet were of one piece act onmem j 01:) connected together this hydraulic drag would rotor to force the pistons aswl t aapescas with respect to each other t fifigfi gig here contemplated, wherein the point of contact equal and opposite, Th angularjt f the 0 of the head with the reaction member is ofiset tons and th tap t causes the tappets to em a sufiicient distance from the axis to cause the age the reaction member at points offset from taippet to rbtaite i speeds and pressures their axes so that the frictional contact of the Wlthout excesslve fnctlon. the tappet is subject tappets with the reaction member causes the tap- 45 to Stavere .stresses at the Jlmcture Of.the shank pets to rotate and 1.011, rather than slide Over PQI'LIOHYWIFIJ. the head portion. By using a small the s rfa of the reaction member. diameter piston with a relatively larger diameter The angularity of the pistons and tappets is tappet the tappets become large enough and str 11 by the f ij f 3 dlvldefl Into two components, 5 vention is more fully disclosed with reference to one o w ch is directed axially of the pistons and th accompanying drawings in which tappetaand the otherof which is directed radially Fig. 1 is a fragmental lon itudinal cross secof the pistons and tappets and therefore subv I tion, and stantlally lengthwise of the rotor. Because the Fig. '2 is a fragmental transverse cross section.

designates a pump housing pistons and tappets are disposed at angles which 55 More specifically, l

in which a stationary pintle 2 is mounted. Rotatably supported by the pintle 2 is a rotor 3 which is connected to a drive shaft 13, joumalled in the housing I, and having means H for connection to a motor drive. The rotor 3 is formed with two banks of cylinder bores 4 each having an axially aligned tappet-guide bore 5. The tappettwo banks of cylinder and tappet-guide bores are arranged at equal and opposite angles, as viewed in longitudinal cross section, inv what might loosely be termed a V relationship. v

Slidably disposed in each cylinder bore 4 is a piston 8, the outer end of which extends into the associated tappet-guide bore 5. Each piston hasa close hydraulic flt with its respective cylinder bore. In each tappet-guide bore 5 is a tappet I the shank portion of which is larger than the piston and which has an enlarged head 8 disposed exteriorly of the rotor. Each tappet head has the shape of a zone of 'a sphere, and the inner end of each tappet is crowned and contacts the outer-end of the adjacent piston. The crowned end acts as anti-friction means which enables each tappet to rotate freely with respect to the piston it actuates. The center of the spherical zone falls on the axis of the tappet at a point within the tappet-guide bore.

The pintle 2 is formed with fluid intake ports 9 and with fluid outlet ports It with which the inner ends of the cylinder bores 4 successively communicate as the rotor 3 revolves about the pintle. An elliptical reaction ring ll, supported by the housing I, surrounds the rotor I, and is so disposed that it permits the pistons and tappets to move outwardly under the influence of centrifugal force while the cylinder bores l are in communication with the fluid inlet ports 9,

and so that it forces the tappets and consequently the pistons inwardly when the cylinder bores are in communication with the fluid outlet ports Hi. It will be noticed, upon reference to Fig. 1, that the angularity of the tappet-guide bores is such that the point of contact between each tappet and the reaction ring is oflset from the axis of the tappet, so that the tappets rotate and roll freely, rather than slide over the surface of the reaction ring. This combined rotary and reciprocatory movement, along with the comparatively large bearing surface which each tappet has in its tappet-guide bore, contributes to long useful life in the presence of extremely high pressures.

The reaction ring H is retained against rotary movement by a pin l2, pressed into the wall of the housing I, and engaging in a hole in thering.

Although a specific embodiment of the invention has been illustrated and described it will be understood that various structural changes may be made within the scope of the appended claims without departing from the spirit of the invention, and such changes are contemplated.

What I claim. is:

1. In a device of the class described, a rotor having a multiplicity of banks of cylinder bores disposed at equal and opposite angles and a tappet-guide bore substantially axially aligned with each cylinder bore and of relatively larger diameter than said cylinder bores, fluid inlet and outlet means for said cylinder bores, a piston in each cylinder bore, a tappet in each tappet-guide bore with one end engaging'the associated piston and its other end extending outwardly of said rotor, and a reaction ring surrounding said rotor. the outwardly extending ends of said tappets being rounded and" engaging said reaction member, said equal and opposite angularity of said banks being such asto dispose the tappets angularly with respect to the reaction member so that the point of contact of said rounded ends is offset from the axes of the tappets and induces rotation of said tappets through contact therewith.

2. In a device of the class described, a rotor having a multiplicity of banks of cylinder bores disposed at equal and opposite angles and a tappet-guide bore of relatively larger diameter substantially axially aligned with each cylinder bore,

' said rotor having an enlarged chamber separating each cylinder bore and tappet-guide bore and a vent port opening said enlarged chamber to the exterior of said rotor, fluid inlet and outlet means for said cylinder bores, a piston in each cylinder bore, a tappet in each tappet-guide bore with one end engaging the associated piston and its other end extending outwardly of said rotor, and a reaction ring surrounding said rotor, the

outwardly extending ends of said tappets being.

rounded and engaging said reaction member, said equal and opposite angularity of said banks being such as to dispose the tappets angularly with respect to the reaction member so that the point of contact of said rounded ends is offset from the axes. of the tappets and induces rotation of said tappets through contact therewith.

JAMES F. HOFFE'R. 

